Classical swine fever is a type of infectious disease, which is a disease caused by a pathogen, that is, classical swine fever virus (CSFV), and does not occur in humans or other animals, but once occurring in pigs, most of the infected pigs are not cured and die (Penrith, M.-L., Vosloo, W. and Mather, C. (2011), Classical Swine Fever (Hog Cholera): Review of Aspects Relevant to Control. Transboundary and Emerging Diseases, 58: 187-196). The classical swine fever, classified as a List A epidemic by the World Organization for Animal Health (OIE), and also classified as a first-class epidemic in Korea by the Law on Domestic Animal Epidemic Prevention, is very contagious to pigs, leading to high fatality, accompanied with a high fever and bleeding, and developed into an acute, subacute, or chronic condition. As mentioned above, since the classical swine fever is an infectious disease with high mortality and morbidity, the prevention thereof is recognized as a critical issue to such an extent that the future of the pig industry cannot be guaranteed without eradication of the classical swine fever. Regarding the classical swine fever, a pig is the only natural host, and spread of the classical swine fever is mainly caused by a virus which is capable of infecting all ages of pigs sensitive to the virus. In Korea, for disease control, vaccination with a live vaccine prepared with a modified live virus, LOM strain, has been carried out. Since a live vaccine for the classical swine fever cannot be serologically distinguished from a wild-type virus, recombinant vaccines such as a marker vaccine are globally in development to differentiate antibodies produced by wild-type virus infection and vaccination. Korea has also focused on development of vaccines for practical use to simply and precisely identify antibodies generated by field infection and antibodies generated by vaccination in terms of the use of a vaccine.
Meanwhile, the remarkable development in molecular biology and genetic engineering techniques is also applied to the field of plants, and thus efforts to produce useful bioactive substances from a plant are being steadily made. The production of useful substances in a plant provides various benefits as follows: 1) extraordinary reduction in a production cost; 2) complete elimination of various contaminants (a virus, an oncogene, an enterotoxin, etc.) that may be generated in a popular method in the art (for isolating and purifying a protein following synthesis in animal cells or microorganisms); 3) seed stock management by seeds even in a commercialization stage, unlike animal cells or microorganisms; and 4) supply of the corresponding substance according to an increased demand within the shortest time because, when the demand for the corresponding substance is rapidly increased, the plant system of the present invention is absolutely preferable to the conventional animal cell system in terms of engineering technology or costs required for mass production.
The reason that the method for producing a useful substance from a plant transformed as described above has received attention is a protein synthesis pathway of a plant. Post-translational modification is the key process of the protein synthesis in a mammal, and since the plant has a protein synthesis pathway of a eukaryotic organism, it can produce a very similar protein to a protein expressed in a mammal. However, despite the several benefits mentioned above, techniques for obtaining useful bioactive substances (medically useful proteins, vaccines and industrially valuable enzymes, etc.) from a plant with high efficiency have not yet had much success.